For the lateral adjustment of the web material by devices of the above referred type there have up to now mostly been used conventional screw mechanisms, which are troublesome to handle. It is also known in the art to use ball screw actuators, which can be provided to perform the axial movement for the lateral adjustment via articulated joints. According to prior art these devices, however, have only been able to be used for said second operation, while said first operation has been performed manually, which has required great hand-power. This heavy work has for long been looked upon as a serious drawback of these devices, which in other respects often can be very efficient.